Constellation reviews Crew Exploration Vehicle Aero-science Project Status

by Chris Gebhardt

Completing a series of summer meetings relating the Crew Exploration Vehicle (CEV), the Constellation Program (CxP) undertook a review of the CEV Aero-science Project (CAP). This review provided NASA and CxP with vital information on the critical-path aerodynamic and aerothermal analyses pertaining to the Orion crew capsule’s reentry and various launch abort modes that it will/could experience during flight.

Overall, the summer meeting to discuss CAP revealed that the project is “green” from a schedule/integration and technical perspective; however, CAP is “yellow and growing” in terms of cost overruns.

Essentially, the CAP is broken down into three categories based on Aeroscience products: Loads, Guidance Navigation & Control (GN&C), and Thermal Protection System (TPS).

In turn, the development and implementation of Loads analyses drives the structural design of the Orion crew capsule, the analyses of GN&C drives the mission performance characteristics of Orion, and analysis of the heating environment Orion will face drives the design of the capsule’s TPS.

As such, the CAP provides the “only source of critical-path aerodynamic and aerothermal data fundamental to vehicle performance and design,” notes the CAP Status presentation – available for download on L2.

A2In all, the CAP aerodynamic database (which includes command module reentry, launch abort/vehicle tower jettison, command module and service module altitude aborts, and proximity/re-contact of the Orion crew module and service module) accounts for 60 percent of the static and dynamic aero analyses for the CEV.

The CAP aerothermal database (which includes analyses on thermal environments on the heat shield, back shell, protuberances/cavities, and plume environments to “support design and development of CEV TPS) comprises the remaining 40 percent of the project.

To support these tests and analyses, the CAP created a series of Wind Tunnel Tests (WTTs) for each database. In all, 61 (73 percent) of the 83 WTTs are complete with only 22 remaining.

Of the completed tests, 39 were dedicated to the CAP aerodynamic database and 22 to CAP aerothermal database.

Currently, there are eight pending aerodynamic WTTs and 14 aerothermal WTTs pending.

In all, the WTT data for the aerothermal environment will be augmented via simulations conducted in “ground test facilities by designing tests to investigate specific phenomenon,” notes the CAP presentation.

A3These tests will include analyses on Orion’s docking window and heat shield as well as compression pad testing, heat shield roughness testing, and Orion Reaction Control System temperature sensitive paint imaging.

Furthermore, the CAP will be responsible to collating all the test/analysis information into a single reentry and ascent abort aerodynamic and aerothermal database for the Orion crew capsule project.

“The databases are to be developed, placed under configuration control, and maintained for the life of the CEV Project,” notes the CAP status presentation.

Compellation and maintenance of this database will be supported in large part by the Ames Research Center at Moffett Field in California, the Johnson Space Center in Houston, Texas, the Marshall Space Flight Center in Huntsville, Alabama, and the Langley Research Center in Hampton, Virginia.

These centers will provide “project level support and coordination, computational resources, ground-based testing resources, analysis resources, and databases generation resources.”

A5Lastly, the presentation notes that the CAP is currently on schedule with their analyses in relation to the overall Constellation Program timeline. However, the schedule is “Green Light” – meaning success oriented.

Seeing that the aerodynamic and aerothermal database is the critical-path item toward the CEV Critical Design Review, a significant delay or set back in terms of collecting, analyzing and collating data could lead to a delay to the Critical Design Review.

Since the nature of the Crew Exploration Vehicle is constantly changing, the CEV currently runs the risk of creating black-out zones for various abort modes as weight and redesign changes continue to develop.

As such, the aerothermal and aerodynamic database’s “accuracy and reliability must be closely coupled with CEV design and operational changes” regardless of CEV milestones slips to later dates.

L2 members: Documentation – from which the above article has quoted snippets – is available in full in the related L2 sections, now over 4000 gbs in size.

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